Figure 7.

Results from the BBCEAS calibration experiment, showing both the raw output voltage and inverse voltage of the same measurement. The darker points are the data; the horizontal lines are the error ranges of the concentration. The experiment demonstrated sensitivity up to 400 $\mathsf{\mu }\mathrm{g} {\mathrm{m}}^{-3}$ as shown in (a). Although at high concentrations, the voltages from the sensors becomes quite low, in most atmospheres, NO₂ does not often surpass 50 ppb. For concentrations less than 100 $\mathsf{\mu }\mathrm{g} {\mathrm{m}}^{-3}$, both normal and inverse voltage can be seen as approximately linear. Graph (b) shows the data for inverse voltage at low concentrations.